This invention concerns a system for the attachment of a sensor that senses information opposite to, and at an air gap's distance from, the coder of a bearing, a sensor designed to be attached to such a system, an ensemble formed by the attachment system and the sensor together, as well as a bearing equipped with such an ensemble.
When bearings of this kind are equipped with a sensor of the rotation speed, angular position, and/or rotation direction, they can be used in particular for automobile wheels that are equipped with an antilock system for said wheels, with the information then being used by a computer to help with braking.
One of the problems that arises with bearings of this kind concerns the attachment of the sensor opposite, and at an air gap's distance from, the coder that generates the impulses that the sensor is to detect. In fact, particularly in magnetic detection technologies, the control of the air gap directly governs the quality of the signal detected.
It is known, for example from document EP-0743526, that a sensor can be integrated into a detachable connector, with said connector being designed for placement in a housing created in a cap associated with the bearing.
This type of solution has numerous disadvantages. In fact, the relative position of the sensor with respect to the coder, and therefore the control of the air gap, depends on manufacturing tolerances of the connector and the housing as well as the relative positioning of these two elements. In a safety application such a braking assistance, the mechanical tolerances do not offer sufficient precision to control the air gap.
In addition, since the connector is detachable, the reliability of the attachment, particularly in a demanding environment such as that of vehicle wheels, cannot be guaranteed, particularly in the case of impact.
Furthermore, since the cap consists of a housing in which the connector is placed, the cap is not sufficiently reliable in waterproofing or protection of the coder.
The system described above also makes it necessary to adapt the size of the cap/connector/sensor ensemble to each bearing size, which runs counter to the standardization pressures in the automobile industry.